Reference voltages in integrated circuits (ICs) are traditionally provided by a bandgap generator, which, in some approaches, has about 3% inaccuracy. For a supply voltage of about 0.9 V or less, the bandgap generator approach is not viable because a voltage used to generate the reference voltage can be greater than about 0.8 V, leaving little room for the reference voltage to be generated.
In various conditions, reference voltages based on the operation of a metal oxide silicon field effect transistor (MOSFET) in the sub-threshold region result in inaccuracy due to process variations, especially when a polysilicon resistor is involved.
Like reference symbols in the various drawings indicate like elements.